About the Term “Substance Dependence”
The term “substance dependence” is very commonly used. In fact, it was one of the two listed substance use disorders (SUDs) in the DSM-IV (APA, 1994), which included “substance abuse” and “substance dependence.” This classification was recently replaced in the DSM-5 (APA, 2013) with the term “substance use disorder” with three levels of severity: mild, moderate or severe. The term “substance dependence” is often used interchangeably with “addiction,” yet the two can be very different. Both of these terms are often inaccurately applied to mean physiological dependence. This confusion can result in communication problems among clinicians and treatment decisions that are not in the best interest of patients. This confusion is furthered by the professional literature. For example, “Addiction is a condition in which the body must have a drug to avoid physical and psychological withdrawal symptoms. Addiction’s first stage is dependence” appears in the American Psychological Association’s publication the APA Addiction Syndrome Handbook (Shaffer, 2012). Notice that no distinction is made between “substance dependence” and “physiological dependence.”
For example, because of the confusion between addiction/substance dependence on one hand and physiological dependence on the other, some clinicians are unwilling to suggest antiaddiction medications, particularly agonists like methadone or buprenorphine or even antagonists like naltrexone or the extended-release, injectable formulation of naltrexone, Vivitrol, to treat opioid dependence. The reasoning behind this refusal comes from the notion that if people are using a drug (the agonist), they are still addicted. In reality, when using agonist drugs, if individuals are not abusing their agonist or any other psychoactive substance, they remain physiologically dependent. Consider patients who use an opioid as prescribed for a couple of months, and who have not abused it or any other psychoactive substances. Upon abrupt discontinuation, they are likely to suffer opioid withdrawal symptoms, but because they are not addicted with its characteristics of compulsion, loss of control, continued use in spite of adverse consequences, and craving, they do not go looking for a fix.
In both the DSM-IV and DSM-5, two of the diagnostic criteria for dependence include an increase in tolerance and the presence of a withdrawal syndrome, both indications of physiological dependence. However, in the DSM-IV, individuals could meet three of the seven criteria for dependence without meeting the ones for tolerance or withdrawal. In the DSM-5, people could meet six or more of the eleven diagnostic criteria indicating a severe level of SUD, again without meeting the criteria indicating physiological dependence. Clearly, substance dependence or addiction may be related to physiological dependence, but the three are different terms although more than one may be applicable to the same situation.
Consider drugs not usually considered to be addictive. Take the case of individuals who use a beta blocker to control blood pressure for some period of time and then suddenly stop. The result is a spike in blood pressure and pulse, maybe tremors, and possibly a fatal heart attack. Or if people use Dilantin for the control of seizures and suddenly stops, they will experience an increase in seizures above baseline, and one could be fatal. Could this be withdrawal, or perhaps a rebound phenomenon?
If individuals use an addictive substance long enough and heavily enough to be able to show withdrawal symptoms when they stop, that alone is evidence of physiological dependence. Conversely, the presence of a withdrawal syndrome when using a psychoactive substance says nothing about whether individuals should be considered addicted.
Further complicating and confusing the issue of what should be clear distinctions between these terms is the result of the addition of gambling to SUDs in the DSM-5. In the DSM-IV, “pathological gambling” was considered an impulse control disorder (APA, 1994). It is now classified as “gambling disorder” in the DSM-5 and listed under the category of “substance use and addictive disorders” (APA, 2013). While I would have no disagreement that gambling can become an addictive disorder, what has occurred since the publication of the DSM-5 is that all of the disorders in this category have come to be regarded as addictions, including all severities of SUDs.
Let us use as an example the use of alcohol. If individuals were to be diagnosed with an alcohol use disorder, mild, in the DSM-5 this would be comparable to the diagnosis of alcohol abuse in the DSM-IV. When speaking about abuse, it is helpful to consider this as intentional drinking or drug use and intoxication. Clearly, college students who set out to get high, “smashed” or drunk were motivated to achieve that state. They made a conscious decision to achieve this end result, which is not the consequence of loss of control or compulsion or craving. This change in considering a mild severity of SUD as an addiction would likely add twenty million people as addicts (Frances, 2013).
Abusive, heavy or binge drinking—let’s go back to the college student example—might result in a hangover for individuals. But a hangover is very different from withdrawal. The symptoms associated with a hangover (e.g., headache, nausea, dizziness, and cotton mouth) are the results of ingesting a large amount of a toxic substance: alcohol. Withdrawal, on the other hand, is defined as “a maladaptive behavioral change, usually with uncomfortable physiological and cognitive consequences, that is the result of cessation or reduction in heavy and prolonged substance use” (Reis, Fiellin, Miller, & Saitz, 2014). The last thing that individuals suffering from hangover symptoms want do is drink the next morning, although they may do so to treat their symptoms with “the hair of the dog that bit you.”
I would like to suggest a replacement for the term “substance dependence,” but cannot find a good substitute. In the meantime, what we can do is use these terms precisely and appropriately.
Acknowledgements: My thanks to Steve Coulter, MD, for his thoughts on this matter.
American Psychiatric Association (APA). (1994). Diagnostic and statistical manual of mental health disorders (4th ed.). Washington, DC: Author.
American Psychiatric Association (APA). (2013). Diagnostic and statistical manual of mental health disorders (5th ed.). Washington, DC: Author.
Frances, A. (2013). Saving normal: An insider’s revolt against out-of-control psychiatric diagnosis, DSM-5, Big Pharma, and the medicalization of ordinary life. New York, NY: Harper Collins.
Reis, R. K., Fiellin, D. A., Miller, S. C., & Saitz, R. (Eds.). (2014). The ASAM principles of addiction medicine (5th ed.). Philadelphia, PA: Wolters Kluwer.
Shaffer, H. J. (Ed.). (2012). APA addiction syndrome handbook. Washington, DC: American Psychological Association.